A mold material castable to provide a mass reduced work piece machinable to produce a mold.
Conventional mold production can involve the purchase of foam modeling material which can be machined and utilized as a mold for the production of molded or formed parts at high temperature (hereinafter referred to as “high temperature foam material”), such as the foam modeling material Renshape 460 available from Huntsman International LLC, Belgium. A plurality of pieces of the high temperature foam material can be joined to produce pieces of high temperature foam material of sufficient size to machineably produce a high temperature foam mold. A surface coat may be applied to the machined high temperature foam mold to generate a surface on which parts can be molded at temperatures typically at or above 175° Fahrenheit (° F.).
However, there remain long felt but unresolved problems with conventional high temperature foam molds. A first substantial problem with convention high temperature foam molds can be that the high temperature foam material comes in relatively small pieces and a plurality of the pieces must be joined to generate high temperature foam material pieces of sufficient size from which a high temperature foam material mold can be produced. However, when a plurality of high temperature foam material pieces are joined the joints of the joined piece of high temperature foam material can manifest incongruities in the surface of the high temperature foam mold which can transfer to the molded parts. Additionally, the joints in a high temperature foam mold exhibit different material characteristics than the body of the high temperature foam material. This difference in material characteristics between the joints and the body portions of the high temperature foam mold can cause the pieces of a high temperature foam mold to travel, exhibit flexure, or bend about the location of the joint(s), each such occurrence altering the configuration of the high temperature foam mold.
Another substantial problem with conventional high temperature foam molds can be that the high temperature foam material alters configuration under increased atmospheric pressures or increased atmospheric pressures and increased temperatures. Molded parts are often molded, formed or cured at temperatures and pressures greater than ambient temperatures and pressures. When utilizing high temperature foam molds the temperatures and pressures must be adjusted within ranges of temperatures or pressures which may not be optimal but serve to avoid altering the configuration of the high temperature foam mold during the molding or curing of molded parts. None-the-less, at increased temperature and pressure a high temperature foam mold may rapidly degrade and only have a life span sufficient to generate a few molded parts (in some circumstances only one or two molded parts).
A related substantial problem with high temperature foam molds can be that the high temperature foam material cannot be utilized or has low utility at atmospheric pressures used to generate vacuum molded parts. At pressures below ambient pressure (or at atmospheric pressures at which molded parts are vacuum formed) the high temperature foam material can expand sufficiently to alter the configuration of the high temperature foam mold, cause damage to the high temperature mold, or otherwise alter the high temperature foam material, such that it can no longer be utilized for the molding or forming of molded or formed parts.
Another related problem with high temperature foam molds can be that the coefficient of thermal expansion of the high temperature foam material is too great in the context of the temperatures which must be utilized to produce a particular molded part. That is, expansion of the high temperature foam mold is too great over the range of temperatures at which the molded parts are formed.
Another substantial problem with high temperature foam molds can be that the high temperature foam material is prohibitively expensive to use for production of a high temperature foam mold. This may in the first instance due to the cost of the high temperature foam material or in the second instance the amount of labor required to join the plurality of pieces of high temperature foam material, or may be due to both the material and labor expense.
Another substantial problem with high temperature foam molds can be that the grain of the high temperature foam material can transfer to or print through to the molded or formed parts. This is particular true when the material from which molded parts are produced has a hardness which is greater than the hardness of the high temperature foam material.
Another substantial problem with high temperature foam molds can be that they cannot be used in press molding. Currently, to perform press molding metal or concrete molds are utilized to withstand the temperatures or pressures or both exerted on the mold.
As an alternative to using high temperature foam molds, other types of conventional mold materials can be utilized such as concrete, thermal plastic resins, or other materials which are compatible with molding parts on the external surfaces at temperatures and pressures as above-described. A significant problem with molds made from these conventional materials can be that finished molds are solid and have great mass. The mass of these conventional molds may not be reduced because the conventional mold material when prepared and prior to being cured may not be compatible with other materials, or may not be applied to the surface of other materials in manner that allows the conventional mold material to bond or remain fixed to the surface of other materials. As such, a sufficiently thick layer of these conventional mold materials may not be generated over the surface of lighter materials.
Another significant problem in using conventional mold materials including those mold materials prepared from mixing and curing conventional ratios of gypsum, melamine formaldehyde resin, and acrylic copolymer cross linked with an ammonium chloride can be that the molds warp at the temperatures at which molded parts are molded due to non-uniform thermal expansion of the conventional mold materials. Warping of conventional mold materials at temperatures at which molded parts are produced transmits the warp to the molded parts.
The inventive mold materials, mold compositions, composition formulations and methods of utilizing such mold materials, mold compositions, or composition formulations to produce molds and molded parts described herein addresses each of the long felt but unresolved problems with the production and use of conventional high temperature foam molds.